09/10/2012

Felix Baumgartner plans to leap from just under 23 miles above the Earth's surface tomorrow, in what will be the world's highest ever skydive. A helium balloon will carry the Austrian to an altitude of 120,000 feet. If successful, his jump will break both a 52 year sky-diving record and the sound barrier.

08/10/2012

NASA's Hubble Space Telescope captured a new image of the spiral galaxy known as ESO 498-G5. One interesting feature of this galaxy is that its spiral arms wind all the way into the center, so that ESO 498-G5's core looks like a bit like a miniature spiral galaxy. This sort of structure is in contrast to the elliptical star-filled centers (or bulges) of many other spiral galaxies, which instead appear as glowing masses.

Astronomers refer to the distinctive spiral-like bulge of galaxies such as ESO 498-G5 as disc-type bulges, or pseudobulges, while bright elliptical centers are called classical bulges. Observations from the Hubble Space Telescope, which does not have to contend with the distorting effects of Earth's atmosphere, have helped to reveal that these two different types of galactic centers exist. These observations have also shown that star formation is still going on in disc-type bulges and has ceased in classical bulges. This means that galaxies can be a bit like Russian matryoshka dolls: classical bulges look much like a miniature version of an elliptical galaxy, embedded in the center of a spiral, while disc-type bulges look like a second, smaller spiral galaxy located at the heart of the first -- a spiral within a spiral.

The similarities between types of galaxy bulge and types of galaxy go beyond their appearance. Just like giant elliptical galaxies, the classical bulges consist of great swarms of stars moving about in random orbits. Conversely, the structure and movement of stars within disc-type bulges mirror the spiral arms arrayed in a galaxy's disc. These differences suggest different origins for the two types of bulges: while classical bulges are thought to develop through major events, such as mergers with other galaxies, disc-type bulges evolve gradually, developing their spiral pattern as stars and gas migrate to the galaxy's center.

ESO 498-G5 is located around 100 million light-years away in the constellation of Pyxis (The Compass). This image is made up of exposures in visible and infrared light taken by Hubble's Advanced Camera for Surveys. The field of view is approximately 3.3 by 1.6 arcminutes.

05/10/2012

Chemist Sven Hovmöller of Stockholm University had been trying for nearly a decade to determine the structures of materials known as quasicrystals and their nearly identical approximants. Thought to be physically impossible until some 30 years ago, quasicrystals are aperiodic structures—meaning they don’t display the rigidly repeating patterns characteristic of crystals like sodium chloride, for example. Since their discovery in the lab, physicists had been working tirelessly to better understand the structure of quasicrystals. But because the existence of such materials was doubted for so long, computer programs currently used to interpret imaging data aren’t equipped to analyze the aperiodic structures.

Hovmöller has worked on and off in the field of quasicrystals for more than 25 years, focusing primarily on the aluminum-cobalt-nickel (Al-Co-Ni) system. Like other quasicrystal researchers, he studied not the elusive materials themselves but their approximants, which differ in atom placement by only 1 or 2 percent and have more tractable patterns of atomic arrangement. Hovmöller’s interest in quasicrystals was piqued when he saw a conference poster displaying an electron microscopy image of one of the Al-Co-Ni approximants. The image was “so beautiful, so clear, [that] it should be possible to solve it,” recalls Hovmöller, who immediately invited Markus Döblinger, the student who made the poster, to do a postdoc in his lab.

But after months of further electron microscopy studies, the duo couldn’t seem to solve the structure. “Not only him and me, but other people also involved, tried so hard, but we didn’t get anywhere,” Hovmöller recalls. “It was extremely annoying."

The image was so beautiful, so clear, that it should be possible to solve it.

—Sven Hovmöller, Stockholm University

Döblinger eventually moved on to the University of Munich, but Hovmöller couldn’t let the idea go. “Every year, once or twice, I [tried] to solve these things, and I just couldn’t.” Then, last summer, he had a seemingly off-the-wall idea. He’d enlist the aid of his 10-year-old son, Linus. “I thought, He’s a smart guy; maybe he could help me,” Hovmöller says.

The father-and-son team sat at the kitchen table for 2 days, poring over the dozens of electron microscopy images Döblinger had generated, as well as some X-ray diffraction data, which provides more precise information on the materials’ atomic positions. Hovmöller would explain to Linus what he was thinking about how the images all fit together, and when Linus didn’t understand something, he’d interrupt his father to ask. This made Hovmöller realize that he was rushing to conclusions. When he slowed down to clear up Linus’s confusion, he’d get new ideas. “In 2 days, we solved four new structures.”

They published their findings in a special issue of Philosophical Transactions of the Royal Society A honoring the 85th birthday of Alan Mackay, who had predicted the existence of quasicrystals before they were identified in 1982. Linus was listed as a coauthor on the paper (370:2949-59, 2012).

“A kid [who] is clever and good at spatial things might well come up with a solution to a problem like that,” says surface physicist Renee Diehl of Penn State University. “I think there’s probably a lot of potential in 10-year-old kids that we’re not tapping.”

And in fact, Linus isn’t as unlikely a character as one might expect in the field of quasicrystals. “There have been a lot of highly creative and unusual people associated with the field,” says Carnegie Mellon University theoretical physicist Mike Widom. Amateur mathematician Robert Ammann, for example, made several significant contributions to quasicrystal theory before the crystals were even proven to exist. Others have pointed to the links between quasicrystals and art, such as aperiodic tilings and mosaics found in Persia. There’s even a company, called Zometool, that manufactures toys used to model quasicrystalline shapes, Widom notes. “The field is quite rich … [in] unusual personalities,” he says. “This boy is in the tradition of the field attracting some nontraditional scientists.”

But all the structures of the Al-Co-Ni quasicrystal and its approximants aren’t exactly solved. “What Sven Hovmöller did is quite nice,” says Walter Steurer of the Laboratory of Crystallography at ETH Zurich, but his methods are qualitative. Thus, Hovmöller and Linus merely mapped out some of the repeating motifs in four of the approximant structures, but “did not publish any atomic coordinates.” The precise locations of some of the crystals’ atoms have yet to be pinpointed.

“A lot of the interesting controversy in the field of quasicrystals has to do with fairly fine details,” which are critically important to understanding the materials’ true structures, Widom says. “You can know where 90 percent of the atoms are, but still not really know the structure because a minority of the atoms are doing interesting and crucial things. . . . What [Hovmöller and Linus] give us is a good starting point for future structure refinement.”

But if someone eventually solves the true structure of the Al-Co-Ni quasicrystal or its approximants, it won’t be Linus. “He’s refused” to work on the remaining structures, Hovmöller says with a laugh. “He’s still a little bit tired” from the last bout of structure solving.

03/10/2012

If President Barack Obama wants to win over the space geeks watching tonight's (Oct. 3) debate, he might consider mentioning that he's the only candidate who's made his mark on Mars ... literally.

Obama will square off against Republican challenger Mitt Romney tonight in Denver for the 2012 presidential election's first debate, which covers domestic policy. The two contenders' visions for the nation's space program may well come up, at which point Obama could mention that his autograph has been cruising around Mars for nearly two months.

The president's signature is etched on a plaque that technicians affixed to the deck of NASA's Curiosity rover before it launched from Florida's Cape Canaveral Air Force Station on Nov. 26, 2011.

As galaxies feverishly churned out new stars in the early universe, the huge black holes at their hearts were firing off intense bursts of energy, a new study reveals.

The discovery could help explain why more massive galaxies host more massive central black holes, researchers said. And the find sheds light on the dynamics and growth of so-called "active galaxies" such as quasars, which were abundant in the early universe.

By contrast, many modern galaxies, including our own Milky Way, are inactive, with quiet central black holes and very low star-forming rates.

Black holes might seem too monstrous to keep company, but surprising new findings suggest they can live in groups within clusters of stars inside our Milky Way galaxy, researchers say.

The presence of multiple black holes within these clusters might drastically alter the way way these major components of galaxies evolve, scientists added.

"Before this work, there were zero black holes known in Milky Way globular clusters, so even finding one would have been exciting," said lead study author Jay Strader, an astronomer at Michigan State University in East Lansing.

Black holes are the densest objects in the universe, with the largest ones, found at the centers of galaxies, containing millions to billions times more mass than the sun. Stellar-mass size black holes are born from the explosive deaths of stars known as supernovas.

Hundreds of black holes, each with the mass of a star, probably form in globular clusters, spherical collections of hundreds of thousands of stars that orbit the center of the galaxy. However, past research suggested these clusters would never house multiple black holes at any one time. Since black holes are so massive, they tend to fall toward the center of globular clusters, similar to how denser materials made their way to Earth's center during its formation. At the hearts of clusters, these black holes would gravitationally tug at each other and tend to kick all, or perhaps all but one, out of the clusters.

Based on radio emissions, however, scientists have apparently discovered a pair of black holes within the large globular cluster M22, located about 10,600 light-years away in the constellation Sagittarius, near the Milky Way's bulge. M22 is one of the brightest globular clusters in the night sky, and holds nearly a million stars.

Rudyard Kipling’s Just So Stories tell tales not so much of evolution, but of the magic and wonder of the animal world. He describes the wizard who gave the camel a hump for its laziness, and the alligator who snapped and stretched the nose of a naïve young elephant to its current lengthy proportion. Those delightful fables, published some 70 years after Jean-Baptiste Lamarck’s death, provide entertaining explanations for such evolved traits, and were clearly inspired by Lamarck’s description of adaptive change, not Charles Darwin’s. In his 1809 publication Philosophie Zoologique, Lamarck wrote of the giraffe, from whose habit of reaching for the green leaves of tall trees “it has resulted . . . that the animal’s forelegs have become longer than its hind legs, and that its neck is lengthened to such a degree that the giraffe, without rearing up on its hind legs . . . attains a height of six meters.”

Although biologists have generally considered Lamarck’s ideas to contain as much truth as Kipling’s fables, the burgeoning field of epigenetics has made some of us reconsider our ridicule. While no biologist believes that organisms can willfully change their physiology in response to their environment and pass those changes on to their offspring, some evidence suggests that the environment can make lasting changes to the genome via epigenetic mechanisms—changes that may be passed on to future generations.